code: def test_conversion_special_characters_in_feature_names(self):
      # this test should fail if conversion function does not implement the
      # special characters in feature names fix
  
      # test both sklearn wrapper and raw booster
      for model in [
          self.xgb_model_special_chars,
          self.xgb_regressor_special_chars,
      ]:
          # process as usual
          output_name = "target"
          spec = xgb_converter.convert(
              model, self.feature_names_special_chars, "target"
          ).get_spec()
  
          self.assertIsNotNone(spec)
  
          # Test the model class
          self.assertIsNotNone(spec.description)
          self.assertIsNotNone(spec.treeEnsembleRegressor)
  
          # Test the interface class
          self.assertEqual(
              spec.description.predictedFeatureName, "target"
          )
  
          # Test the inputs and outputs
          self.assertEqual(len(spec.description.output), 1)
          self.assertEqual(spec.description.output[0].name, "target")
          self.assertEqual(
              spec.description.output[0].type.WhichOneof("Type"),
              "doubleType",
          )
          for input_type in spec.description.input:
              self.assertEqual(
                  input_type.type.WhichOneof("Type"), "doubleType"
              )
          self.assertEqual(
              sorted(self.feature_names_special_chars),
              sorted(map(lambda x: x.name, spec.description.input)),
          )
  
          # Test the linear regression parameters.
          tr = spec.treeEnsembleRegressor.treeEnsemble
          self.assertIsNotNone(tr)
          self.assertEqual(len(tr.nodes), 23)
  
file_path: coremltools/coremltools/test/xgboost_tests/test_boosted_trees_regression.py
imports: import json
  import tempfile
  import unittest
  from coremltools._deps import _HAS_SKLEARN, _HAS_XGBOOST
  from coremltools.models.utils import _macos_version
label_desc: Use image node_id 6 for calling the BoostedTreeRegressorXGboostTest obj's underlying member method code with example usage: obj.test_conversion_special_characters_in_feature_names() without return types